In the related art, in order to introduce air in a vehicle cabin to an installation portion of an indoor temperature sensor that detects temperature in the vehicle cabin, a vehicle air conditioner employs an aspirator that decreases pressure by means of the Venturi effect. The aspirator is provided with a nozzle that sucks in, as secondary air, the air in the vehicle cabin via the installation portion of the indoor temperature sensor, a main unit that forms an air channel so as to surround the outer circumference of this nozzle, a primary-air introducing unit that introduces, as primary air, a portion of an airflow circulating inside an air conditioning unit into the air channel of the main unit, and a diffuser that is connected to an open end of the main unit and that is configured such that the tip of the nozzle opens in the vicinity of a throat portion of the diffuser.
With such a vehicle air conditioner, in order to detect the temperature in the vehicle cabin with high precision, it is necessary to introduce a sufficient amount of vehicle interior air to the installation portion of the indoor temperature sensor, and, accordingly, it is necessary to introduce a sufficient amount of the primary air into the aspirator that sucks in the vehicle interior air as the secondary air. Therefore, as shown in FIG. 3, in order to guide a portion of an airflow flowing in the direction of an arrow Y in an air channel 2 in a case main unit 1 toward an aspirator 4, Patent Literature 1 discloses a unit in which a guide 3 protrudes into the air channel 2 from an area surrounding a primary-air introducing unit 5 of the aspirator 4.
On the other hand, in order to directly blow the primary air introduced into the aspirator into the vehicle cabin, it is desirable to introduce temperature-adjusted air, and, in this case, the aspirator needs to be installed in a region on the downstream side of an air-mixing damper. However, there are many restrictions related to the region on the downstream side of the air-mixing damper, because mode-switching dampers, means of enhancing the air-mixing performance, and so forth are installed therein, which makes it difficult to install an aspirator provided with a guide while avoiding interference with such equipment, and thus, it is necessary to employ a special structure, for example, by providing a through-hole for introducing the primary air into the aspirator at a rotation shaft of a mode-switching damper, as disclosed in Patent Literature 2.